For many years it was common practice to mow hay and other forage crops with a mower, such as a sickle bar, let the crop lie in the field for a sufficient period to reasonably dry the same, and then utilize a windrower, usually pulled by a tractor, to dispose the cut and at least partially-dried crop into a windrow in order that a baler could be employed to pick up the windrow and convert the same into bales of the crop. One reason for letting the crop lie in the field to dry was especially for purposes of letting the stalks dry a sufficient amount in order that the material when baled would not be subject to mold or internal combustion.
To obviate the need for letting the crop lie in the field to dry as described above, more recent practice has employed a self-propelled windrower or combination windrower and stalk conditioner which, in general, are of several types. A windrower per se has a head of substantial width and a cutter bar extends across the full length of the forward edge thereof. A consolidating auger also is included in the machine which is as wide as the cutter bar and this consolidates the material into a relatively narrow windrow which lies upon the field. To enhance the drying of the material, a windrower of this type also can include conditioning rollers which are actually a pair of crushing rollers that engage the material after being consolidated by the auger and crush the stems and stalks of the material and then discharge the same in the form of a windrow upon the field.
In a combination mower-conditioner, said machines also have a head of substantial width and a cutter extends across the full length of the forward edge thereof. A reel of the same length as the cutter engages the cut material and moves it rearwardly into contact with conditioning rollers which coact to crush the stems and stalks of the material, said rollers being of substantially the same width as the cutter and reel. Consolidation of the conditioned material is effected by angular baffles extending inward and rearwardly within the head and function to discharge the material into a windrow after discharge from the conditioning rollers and engagement by the baffles.
In both of the above descriptions of machines, drive wheels are provided thereon which are driven by an internal combustion engine, such as a diesel engine or otherwise, that operates hydraulic pumps interconnected to individual hydraulic motors respectively connected to the drive wheels to rotate the same independently of each other. By controlling the relative speeds of said drive wheels and/or the direction of rotation thereof, turning of the machine can be effected as distinguished from employing a steering wheel or wheels as in certain other types of agricultural equipment. In a mower-conditioner, the drive wheels are spaced farther apart than in a windrower to permit leaving a swath of the cut material as distinguished from a relatively narrow windrow, whereas in a windrower, the drive wheels are closer together than in a mower-conditioner because only a relatively narrow windrow is produced by the windrower. However, in view of the fact that the present invention is concerned with safety means associated with the control of the speed and directions of the drive wheels, several different embodiments of safety means are respectively provided by the present invention for use on windrowers and mower-conditioners. Hence, in windrowers, the pumps are near the wheels and the motors are closer together than in mower-conditioners.
To illustrate the type of machines to which the safety mechanism, comprising the essential aspects of the present invention, applies, attention is directed to U.S. Pat. No. 3,563,109 to Glass et al, dated Feb. 16, 1971, and U.S. Pat. No. 3,777,833, to Koch, dated Dec. 11, 1973. In these patents, it will be seen that pairs of drive wheels are employed which are actuated by hydraulic motors powered by hydraulic pumps and individually controlled as to speed and direction by a steering column interconnected by links to the hydraulic pumps, and a speed control lever also is manually operable to control the delivery of hydraulic fluid to the motors equally. In the Glass et al patent, a latching plate is engageable by the speed control lever to maintain the same in a desired operative position but the same is moved manually incident to the latching plate and no automatic positioning of the same in neutral is provided.
In the Koch machine, a steering column having a steering wheel on the upper end thereof is rotatable to control the speed of the hydraulic motors individually connected to the drive wheels by determining the discharge of the pumps to the motors and thereby effect hydrostatic steering, as in the Glass et al machine. In addition, a speed control lever is manually operated and normally is held at a given speed by engaging one of a series of spaced notches in a rack. There is no means included for latching the steering wheel in neutral position or otherwise, whereby accidental movement of the steering wheel in either the Glass et al or Koch machine from the neutral position thereof, will cause driving of the machine to be effected and thereby, can result in personal or property damage.
The publication identified as MacDon "SELF-PROPELLED HYDROSTATIC SWATHER-WINDROWER" exists, and a copy thereof is furnished with the instant application. This publication is distributed by MacDon Industries, Ltd., 680 Moray Street, Winnipeg, Manitoba R3J3S3 Canada, the publication being identified as issued June, 1976. A list of components and an expanded illustration of the various arrangements of the components indicates a locking pin adapted to be inserted by a speed control lever into a hole in a plate associated with the steering mechanism, presumably for safety purposes. However, there appears to be no means for biasing the speed control lever to neutral position or otherwise.